By now, you can see the overwealming answer is "ride both!"
Each has its good points and
bad well lets say "not as good" points. Yes, Durango is a modern place compared to Chama, but that can come in handy.
Chama has charm, and its great to be able to wonder around the yard and the engines and nobody bothers you.
Durango has
all the choices you can imagine for places to eat. Chama has few. Antonito... are there any?
The equipment, well we all know the engines are the same. The D&S has the good fortune of having all the vintage
Rio Grande passenger cars, if that matters to you. The C&TS cars are homemade, but very nice to ride, comfortable and nice big windows. Both trains have always seemed to me to be about the same as far as cleanliness -as much as can be expected when pulled by coal burning steamers.
The rides. Both are great! Both have lots of territory that can't be seen from the road. The D&S is the canyon, and you look up at the spectacular mountains.
The C&T climbs the mountain, and you get a wide range from Antonito to Cumbres to Chama. Personally, I like the mountains, and I would enjoy the C&TS more if the speed was faster between Big Horn and Antonito... that's my boring part.
I always get a great sense of "the wild west" unspoiled and undeveloped when I see the view of the valley below Los Pinos loop. Too bad the homes built there at the loop in the last 10-15 years spoiled that part of it. Hopefully it doesn't spread.
BOTH ARE GREAT! BOTH DESERVE OUR PATRONAGE. DON'T CHOOSE, RIDE BOTH!
Big fan of Rocky Mountain Narrow Gauge Railroading, but stuck here in PA.